Battery module

ABSTRACT

A battery module includes a plurality of cells. The battery module also includes a housing configured to substantially enclose the plurality of cells. The battery module further includes a lower tray configured to receive the plurality of cells. The lower tray is located inside the housing adjacent a bottom of the housing and includes a top side and a bottom side. The top side has a plurality of sockets configured to receive the plurality of cells in a closely packed arrangement. The bottom side is configured to define a chamber between the lower tray and the bottom of the housing. The chamber is sealed off from the rest of the battery module and is configured to receive released gas from the plurality of cells.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Patent Application of U.S. patentapplication Ser. No. 12/481,480 now U.S. Pat. No. 7,951,477, filed Jun.9, 2009, which is a Continuation of International Patent Application No.PCT/US2007/087643, filed Dec. 14, 2007, which claims the benefit of andpriority to U.S. Provisional Patent Application No. 60/874,933, filedDec. 14, 2006, U.S. Provisional Patent Application No. 60/988,465, filedNov. 16, 2007, and U.S. Provisional Patent Application No. 60/989,650,filed Nov. 21, 2007.

The disclosures of the following patent applications are incorporated byreference in their entirety: U.S. patent application Ser. No. 12/481,480now U.S. Pat. No. 7,951,477, International Patent Application No.PCT/US2007/087643; U.S. Provisional Patent Application No. 60/874,933;U.S. Provisional Patent Application No. 60/988,465; and U.S. ProvisionalPatent Application No. 60/989,650.

BACKGROUND

The present application relates to battery modules or systems for use invehicles such as hybrid electric or electric vehicles.

There is a need for a battery module design that provides increasedresistance to damage in the event of a vehicle crash. There is also aneed for a battery module that has improved cooling characteristics forthe battery cells included in the module. These needs and other benefitsand advantages are addressed below with regard to the various disclosedembodiments.

SUMMARY

According to one embodiment, a battery module includes a plurality ofcells. The battery module also includes a housing configured tosubstantially enclose the plurality of cells. The battery module furtherincludes a lower tray configured to receive the plurality of cells. Thelower tray is located inside the housing adjacent a bottom of thehousing and includes a top side and a bottom side. The top side has aplurality of sockets configured to receive the plurality of cells in aclosely packed arrangement. The bottom side is configured to define achamber between the lower tray and the bottom of the housing. Thechamber is sealed off from the rest of the battery module and isconfigured to receive released gas from the plurality of cells.

According to another embodiment, a battery module includes a pluralityof cells. The battery module also includes a housing configured tocontain the plurality of cells. The battery module further includes alower tray located inside the housing adjacent a bottom of the housing.The lower tray comprises a plurality of sockets. Each socket isconfigured to receive one of the plurality of cells. The battery modulefurther includes an upper tray located inside the housing adjacent a topof the housing. The upper tray includes a plurality of sockets. Eachsocket is configured to receive the corresponding cell from the lowertray. The battery module further includes a common chamber defined by abottom of the lower tray and the bottom of the housing, the commonchamber configured to receive gas expelled from the plurality of cells.The battery module further includes a seal located on an upper side ofthe lower tray and is configured to seal the connection between theplurality of cells and the lower tray to maintain the gas in the commonchamber. The battery module further includes a clamping plate locatedabove the seal to clamp the seal between the lower tray and the clampingplate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of vehicle with a battery module accordingto an exemplary embodiment.

FIG. 2 is a perspective view of a battery module according to oneexemplary embodiment.

FIG. 3 is a perspective view of the batteries, baffles and trays fromthe battery module shown in FIG. 2.

FIGS. 4 and 5 are perspective views of a battery from the battery moduleshown in FIG. 2.

FIGS. 6 and 7 are perspective views of the battery module shown in FIG.2.

FIG. 8 is a perspective view of the housing for the battery module shownin FIG. 2.

FIGS. 9 and 10 are perspective views of a pack from an alternativeembodiment of the battery module shown in FIG. 2.

FIGS. 11 and 12 are perspective views of trays of the alternativeembodiment of the battery module shown in FIGS. 9 and 10.

FIG. 13 is a perspective view of a battery module according to anotherexemplary embodiment.

FIG. 14 is a perspective partial cutaway view of the battery moduleshown in FIG. 13.

FIG. 15 is a perspective partial cutaway view of the battery moduleshown in FIG. 13.

FIG. 16 is a perspective partial cutaway view of the battery moduleshown in FIG. 13.

FIG. 17 is an exploded perspective view of the battery module shown inFIG. 13.

FIG. 18 is a sectional view of the battery module shown in FIG. 13.

FIG. 19 is an enlarged detail view of the battery module shown in FIG.18.

FIG. 20 is an enlarged detail view of the battery module shown in FIG.18.

FIG. 21 is an enlarged detail view of the battery module shown in FIG.18.

DETAILED DESCRIPTION

For the purpose of this disclosure, the term “coupled” means the joiningof two members directly or indirectly to one another. Such joining maybe stationary in nature or moveable in nature. Such joining may beachieved with the two members or the two members and any additionalintermediate members being integrally formed as a single unitary bodywith one another or with the two members or the two members and anyadditional intermediate members being attached to one another. Suchjoining may be permanent in nature or may be removable or releasable innature.

According to an exemplary embodiment, a battery module includes aplurality of electrochemical cells or batteries arranged in two groups.The batteries are arranged in trays and are surrounded by an outerhousing. The trays include a plurality of sockets, sleeves or hollowsconfigured to align and locate cells. Bus bars or connectors are used tocouple the batteries together and partially by protrusions or walls onthe upper tray to reduce the chance of a short circuit. The lower traysinclude a plurality of protrusions or standoffs and a wall that definesa volume below the cells that is configured to isolate any gases ventedfrom the interior of the cells. Because the gasses vented from the cellsmay be hazardous, it is desirable to contain any vented gasses and keepthem isolated from the environment. The two groups of cells areseparated by a central plenum air space and a divider. The arrangementof the cells allows the module to be compressed thereby reducing damageto the cells when the module is crushed or compressed.

Referring to FIG. 1, a vehicle 10 (e.g., a hybrid-electric vehicle (HEV)or plug in HEV (PHEV)) is shown including a battery module 12 accordingto an exemplary embodiment. While particular exemplary embodiments ofthe battery module are shown and described, it should be understood thatthe size, shape, configuration, and/or position of the battery modulemay vary according to various exemplary embodiments.

A battery module 12 is shown according to an exemplary embodiment inFIG. 2 and includes a housing 14, air baffles 16, 18, two battery packs20, 22, and connectors 24 conductively coupling a plurality of batteriesor cells 26 in a circuit. According to an exemplary embodiment,thirty-two cells 26 are included in the battery module 12. According toother exemplary embodiments, a different number of batteries or cellsmay be included in a battery module.

Each of the battery packs 20, 22 (shown, for example, in FIGS. 9 and 10according to an exemplary embodiment) include a plurality of batteriesor cells 26 and upper and lower trays 30, 32. According to an exemplaryembodiment, and referring to FIGS. 4 and 5, the cells 26 are generallycylindrical lithium-ion cells. According to other exemplary embodiments,the batteries or cells may be another type of electrochemical cell(e.g., Nickel Metal Hydride cells, lithium polymer cells, etc.). Also,the cells may be configured in various suitable geometric configurationssuch as, for example, prismatic, cylindrical, polygonal, etc.

Referring to FIGS. 3, 10, and 11, the bottom or lower tray 32 for thebattery packs 20, 22 is shown. The lower tray 32 includes openings,cutouts or sockets 34 (e.g., depressions, sleeves, hollows, etc.) thatreceive the cells 26 in a closely packed honeycomb-like arrangement(although the cells 26 may be arranged differently according to otherexemplary embodiments). The walls of the sockets 34 help locate andalign the cells 26 to properly space the cells 26 and allow cooling airto pass over and/or around the cells 26.

According to an exemplary embodiment, the cells 26 are arranged in twogroups, banks, or packs 20, 22 with two rows of cells 26 in each pack20, 22. According to other exemplary embodiments, each pack may includethree or four rows of batteries or cells and may be any suitable numberof cells in length. The two packs 20, 22 are separated by a centralplenum, air space or chamber 55 that may include a divider or panel 38,as shown in FIG. 8.

According to an exemplary embodiment, the batteries or cells 26 includea venting mechanism 40 on at least one end thereof (shown as a raisedportion in FIG. 5) that allows the cell 26 to release internal gasses oreffluent if a failure occurs to help avoid damage to the battery casing42. The vents 40 allow a controlled release of gasses if an internalpressure reaches a predetermined limit.

The cells 26 are shown to include positive and negative terminals 44 (asshown in FIG. 4). Thus, the vent mechanism 40 may include a conventionalpressure relief valve or other suitable valve arrangement. Terminals 44of the cells 26 are connected by bus bars or connectors 24.

As shown in FIG. 3, the lower tray 32 includes a wall 50 extendingdownward from the bottom or floor 52 of the lower tray 32 that defines acommon chamber or air space 55 below the cells 26. The lower tray 32includes downward extending posts, protrusions or stand-offs 54 thatsupport the floor 52 of the lower tray 32 over the chamber 55. Wall 50may be about 10 mm in height according to an exemplary embodiment, butmay differ in other embodiments The cells 26 are suspended above thechamber on shelves or ledges extending inwardly from the walls of thesockets 34. The cell vents 40 are in fluid communication with thechamber. In the unlikely event that a cell 26 fails, gasses released bythe cell through the vent 40 will be retained in the chamber and keptgenerally isolated from the environment. The common air chamber may bedirectly or indirectly connected to outside vehicle 10. For instance, ahole or opening in the bottom of housing 14 may fluidly connect thecommon air chamber of released gasses to the atmosphere (for example,through the floor of vehicle 10).

As shown in FIG. 12, the bottom or lower surface 60 of the upper trays30 also includes cutouts or sockets 64 (e.g., depressions, sleeves,hollows, etc.) that receive the cells 26 in a closely packedhoneycomb-like (or other type of) arrangement. Openings 66 in the uppertrays 30 allow terminals 44 (seen in FIG. 4) from the cell 26 to passthrough the upper tray 30.

Bus bars or other suitable connectors 24 are coupled to the cellterminals 44 to connect the cells 26 together to form a circuit. The busbars 24 are received by areas defined by raised projections or walls 68that extend upward from the top surface 62 of the upper trays. The walls68 protect and help to isolate the bus bars 44 to reduce the chance of abus bar 24 or terminal 44 short-circuiting with another bus bar 24 orterminal 44. The walls 68 include slots or other openings (seen best inFIGS. 7 and 9) that allow sensors 70 (e.g. voltage sensors, currentsensors, temperature sensors) to be connected to the bus bars 24 orterminals 44. These sensors 70 are connected to wires 72 that run downthe length of the battery module 12 and pass through an opening 82 inthe outer housing 14 (seen in the left panel in FIG. 8). While sensors70 and wires 72 are shown connecting to only a portion of the cells 26in FIG. 6, according to other exemplary embodiments, sensors 70 may beprovided for all the cells 26 in the battery module 12. Temperaturesensors may be located throughout the battery module 12. An electroniccontrol unit (ECU) may receive input from the sensors and controloperation of the battery module and system accordingly. For example, theECU may control the operation of a cooling system for the battery module12. For instance, the ECU may compare present values of the temperaturesensors to a predetermined value and make the necessary changes to thecooling system (for example, increase, decrease, or maintain the amountof cooling).

According to an exemplary embodiment shown in FIGS. 2 and 3, the uppertray 30 for the two packs 20, 22 may be formed as a single unitary bodyand the lower tray 32 may be formed as a single unitary body. Accordingto another exemplary embodiment, shown in FIGS. 6-7 and 9-12, the uppertrays 30 and the lower trays 32 may be formed as separate bodies. A sealor gasket 36 may be provided around the circumference of the trays 30,32 and around the cell sockets to isolate the common air chamber 55 forreceiving vent gasses from the battery cells from the main volume of thebattery module 12. Cooling air flows through the main volume of themodule and passes over the batteries or cells 26.

The outer housing 14 of the battery module 12 (as shown, for example, inFIGS. 2 and 8) encloses the battery packs 20, 22. The outer housing 14includes a front panel 84, back panel 86, left panel 88, right panel 90,bottom panel 92 and a top panel or cover (not shown). According to anexemplary embodiment, the housing 14 is formed from 1.5 mm thick sheetmetal. The sheet metal may be painted, if desired. According to otherexemplary embodiments, the housing 14 may be a polymer or other suitablematerial.

The housing 14 may include ribbing or other features suitably configuredand positioned to strengthen and add rigidity to the outer housing 14.The housing 14 includes an inlet aperture or opening 94 on the rightpanel 90. The opening 94 is aligned generally with the central plenumair space and two outlet apertures or openings 96 on the left panel 88disposed towards the front and back panels 84, 86. The divider 38 mayrun the length of the central plenum. According to other exemplaryembodiments, the two openings 96 on the left panel 88 may be inlets andthe opening 94 on the right panel 90 may be an outlet. The housing 14may also include an opening on the left, right, front, back, and/orbottom panels 84, 86, 88, 90 that allows vented gas to escape from thelower plenum or chamber 55.

Inlet and outlet air baffles 16, 18 may be provided on the insidesurface of the left and right panels (see, e.g., FIGS. 2, 3 and 8).Additionally, horizontal and vertical filler panels 98 may be providedin the housing 14. These filler panels 98 may be located in the cornersor center of the interior of the outer housing 14. The filler panels andbaffles are configured to provide relatively equal airflow within themodule 12 (e.g., if there were too much space surrounding one of thecells 26 as compared to other cells 26, undesirable low pressure zonesmay be formed within the module 12). The cells 26 in each pack 20, 22are arranged in two offset rows. The air baffles 16, 18 are configuredto maintain an air space between the cells 26 on the ends of the offsetrows and the air baffles 16, 18 that is similar to the air space of theother rows and the walls or panels 84, 86, 88, 90 of the housing 14.Cooling air passes from the opening 94, over the cells 26 and out theopenings 96 to cool the cells 26. In an alternative embodiment, coolingair may pass from the openings 96, over the cells 26 and out the opening94 to cool the cells 26. In another alternative embodiment, airflow maybe bidirectional.

The air spaces provided in the housing 14 (and in the housing 214discussed later) between the battery packs 20, 22 and the front and backpanels 84, 86 of the housing and between the two packs 20, 22 allow thebattery module 12 to be compressed without damaging the cells 26 (e.g.,acting as crumple zones for the battery module 12 in the event of avehicle collision). Generally, the battery module 12 would be placed inan area of the vehicle 10 that is configured to not deform in acollision (i.e. outside a “crumple zone”). But if an object or bodyintrudes into the space occupied by the battery module 12, the batterymodule 12 is configured to be partially crushed or compressed before thecells 26 begin to be deformed. The battery module 12 is designed withinternal crumple zones that allow the module 12 to be compressed, forexample, up to approximately 40% in the longitudinal direction (e.g.,along the length of the module 12 as shown in FIG. 2) withoutsubstantially damaging the batteries or cells 26 included in the module12.

Referring to FIGS. 13-21, another exemplary embodiment of a batterymodule is shown. The embodiment shown in these figures is similar to theembodiment described above and contains many of the same features orelements, as evident from the drawings. Referring to FIG. 17, a batterymodule 212 is shown according to an exemplary embodiment. Battery module212 is shown to include a base plate 252, a lower tray sealing plate250, a lower tray 230, a seal 238, a seal clamping plate 228, andmultiple batteries or cells 226 (arranged in two separate battery groupsor packs). Battery module 212 is also shown to include two wall plenumsor external air chambers 218, a central plenum or central air chamber216, and battery pack end plates 262, 264. Battery module 212 is alsoshown to include a battery disconnect unit (BDU) 300 which includes ahousing, a current sensor, a pre-charge resistor, a pre-charge relay anda contactor. Battery module 212 is also shown to include cell clampingpads 254, upper trays 256, bus bar assemblies 258, a central air chambercover 260, cell supervising controller (CSC) boards 224, CSC covers 222,and a cover or housing 214.

As shown in FIG. 13, a battery module 212 may include a housing 214. Asshown, housing 214 is made from two pieces and comprises a bottom orbase plate 252 and a cover with a top, front, back, first side andsecond side. In an alternative embodiment, housing 214 may be made frommore or less than two pieces. Openings 208 and 210 (shown in FIGS. 13and 17) are provided in housing 214 to provide an inlet and outlet forcooling air from a cooling system. In an alternative embodiment, theseopenings may be located elsewhere on housing 214. Cooling air flow mayenter opening 208 and exit opening 210 or cooling air may enter opening210 and exit opening 208.

Referring to FIG. 14, battery module 212 is shown without the cover orhousing 214 and without one CSC cover 222. Battery module 212 has twoexternal air chambers, one for each battery pack. The external airchamber 218 is shown in FIG. 14 to include openings 220. These openings220 may be generally rectangular as shown or may be any suitable shapeand size. As shown, there is one opening 220 per adjacent cell 226. Inalternative embodiments, there may be more openings 220 per adjacentcell, or there may be openings 220 on less than every adjacent cell. Asshown, external air chamber 218 has a taper in a first direction. Thistaper is to create or allow substantially constant air velocity throughthe battery module 212.

As shown, cooling air enters the external air chamber 218 near the BDU(through opening 210 in housing 214) where there is no taper. Coolingair leaves external air chamber 218 through openings 220, passing by andaround cells 226 to the central air chamber 216. The volume of coolingair decreases as cooling air advances along external air chamber 218.The tapered shape of the chamber 218 functions to create substantiallyconstant cooling air velocity throughout the external air chamber 218.In an alternative embodiment, the air flow may be in a directionopposite of that described above. In yet another alternative embodiment,the external air chamber 218 may allow for bidirectional air flow.

Still referring to FIGS. 15-17, the central air chamber 216 is shown tobe located between the two battery packs. As shown, the central airchamber 216 is configured to receive cooling air from the external airchambers 218 after it passes through the battery packs. Central airchamber 216 may have any number of inlets and outlets. Cooling airenters the central air chamber 216 through openings 240. Openings 240may be any suitable size or shape and may be located in any suitablelocation in central air chamber 216. Cooling air exits the central airchamber 216 though an opening at the end of the central air chamber 216.The central air chamber 216 is shown to include a taper in a firstdirection (vertical) and a second direction (horizontal). These tapersare configured to create substantially constant air flow velocity. Asshown, central air chamber 216 starts out with a relatively small crosssectional area at the beginning of the central air chamber 216 and endswith a relatively large cross sectional area near the exit of thecentral air chamber 216. In an alternative embodiment, cooling air mayflow in a direction opposite of what was just described. For instance,cooling air may enter the large opening of the central air chamber 216and exit through the smaller openings 240. In another alternativeembodiment, the central air chamber 216 may allow for bidirectional airflow.

Referring to FIGS. 15-17, the bottom or lower tray 230 for the batteriesor cells 226 is shown. The cells are arranged into two groups or packs.The lower tray 230 includes cutouts or sockets 242 (e.g., depressions,sleeves, hollows, etc.) that receive the cells 226 in a closely packedhoneycomb-like arrangement (although the cells 226 may be arrangeddifferently according to other exemplary embodiments). The walls of thesockets 242 help locate and align the cells 226 to properly space thecells 226 and allow cooling air to pass over and/or around them. Asshown in FIGS. 15-17, lower tray 230 is a single unitary member. In analternative embodiment, lower tray 230 may be two separate pieces. Thesockets 242 may include shelves or ledges 232 (as shown in FIG. 21) onwhich the cells 226 may rest. Similar to battery module 12, batterymodule 212 includes a common air plenum or chamber 255 between the lowertray 230 and the bottom of the housing 214. The common air chamber isconfigured to receive released gasses from cells 226. The chamber 255 isbounded on the sides by the walls 235 of the lower tray 230 and on thebottom by a tray sealing plate lower 250 and the base plate 252 of thehousing 214.

Referring to FIG. 17, the battery module 212 is shown with upper trays256. Upper trays 256 are similar to the upper trays 30 of battery module12. Upper trays 256 have a greater lead-in tolerance than lower tray232. As such, upper trays 256 perform less of a holding function ofcells 226 than lower trays 232. Cell clamping pads 254 may be used incombination with the upper trays to help even the clamping load orcompression on the cells 226 and to reduce rattle in the battery module212.

Referring to FIGS. 17-21, the battery module 212 is shown to includeseals 238 that are clamped between the lower tray 230 and the sealclamping plates 228. The seals 238 positively seal in any releasedgasses from cells 226. As can be seen in FIG. 21, seals 238 include anextension or flap 244 that presses up against the cell 226. As pressureincreases in the common air chamber, the pressure presses extension 244against cell 226 to aid in sealing. Seal 238 also includes multipleridges or raised portions to help positively (hermetically) seal thecommon air chamber from the rest of the module 212. As discussed above,gasses in the common air chamber may be vented outside the vehicle 10through a hole in housing 214 and vehicle 10.

The cooling system for the battery module 12, 212 may be integrated withthe cooling system for the interior of the vehicle 10 or it may be aseparate cooling system. Cooling air may be connected to battery module12, 212 by duct work, which may be made from, for example, sheet metalor a suitable metal of polymeric material. Cooling air may be pushed(for example, by a fan) through the battery module 12, 212. Cooling airmay also be pulled (for example, by a vacuum pump) through the batterymodule 12, 212. In addition, the cooling air may flow from the centralair plenum or chamber between the battery packs to the external airchamber between the battery packs and the sides or walls of the housing.Alternatively, the cooling air may flow from the external air chamberbetween the battery packs and the sides or walls of the housing to thecentral air plenum or chamber between the battery packs. The cells 26,226 generally conduct heat well in the axial direction. As a result, thearea of the cells covered by the walls of the sockets 34, 64, 242 doesnot significantly reduce the heat transfer from the cells 26, 226 to thecooling air.

It should be noted that references to “front,” “back,” “upper,” and“lower” in this description are merely used to identify various elementsas are oriented in the FIGURES, with “front” and “back” being relativethe vehicle in which the battery assembly is placed.

The construction and arrangement of the elements of the battery modules12 as shown in the illustrated and other exemplary embodiments isillustrative only. Although only a few embodiments of the presentinventions have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited herein (e.g.,materials for formation of the conductive and insulating components,technology for the internal components of the cells 26, the shape of thecells 26, etc.). For example, elements shown as integrally formed may beconstructed of multiple parts or elements, the position of elements maybe reversed or otherwise varied, and the nature or number of discreteelements or positions may be altered or varied. It should be noted thatthe elements and/or assemblies of the battery module may be constructedfrom any of a wide variety of materials that provide sufficient strengthor durability (such as aluminum, steel, copper) in any of a wide varietyof colors, combinations and suitable materials. Other substitutions,modifications, changes and omissions may be made in the design,operating conditions and arrangement of the preferred and otherexemplary embodiments without departing from the scope of the presentinventions. The order or sequence of any process or method steps may bevaried or re-sequenced according to alternative embodiments. Othersubstitutions, modifications, changes and omissions may be made in thedesign, operating configuration and arrangement of the preferred andother exemplary embodiments without departing from the spirit of thepresent inventions as expressed herein.

What is claimed is:
 1. A battery module comprising: a plurality ofcells; a housing configured to substantially enclose the plurality ofcells; and a lower tray configured to receive the plurality of cells andlocated inside the housing adjacent a bottom of the housing, andincludes a top side and a bottom side, the top side having a pluralityof sockets configured to receive the plurality of cells in a closelypacked arrangement, the bottom side configured to define a chamberbetween the lower tray and the bottom of the housing, the chamber beingsealed off from the rest of the battery module and configured to receivereleased gas from the plurality of cells; the housing including anopening configured to fluidly connect the chamber to atmosphere.
 2. Thebattery module of claim 1, further comprising a seal located on the topside of the lower tray and configured to seal the connection between theplurality of cells and the lower tray to maintain the gas in thechamber.
 3. The battery module of claim 2, further comprising a clampingplate located above the seal to clamp the seal between the lower trayand the clamping plate.
 4. The battery module of claim 1, wherein theplurality of cells are arranged in a first cell pack and a second cellpack such that a central air chamber exists between the first cell packand second cell pack.
 5. The battery module of claim 4, wherein thefirst cell pack and the second cell pack each comprise at least two rowsof cells.
 6. The battery module of claim 4, wherein the central airchamber is connected at a first end to a first opening in the housingand at a second end to a second opening in the housing opposite thefirst opening, wherein the first opening is a cooling air inlet and thesecond opening is a cooling air outlet.
 7. The battery module of claim6, wherein the central air chamber is tapered in a first direction andin a second direction in order to provide substantially constantvelocity air flow through the battery module.
 8. The battery module ofclaim 4, further comprising a first external air chamber located betweenthe first cell pack and a front of the housing, and a second externalair chamber located between the second cell pack and a back of thehousing.
 9. The battery module of claim 8, wherein the external airchambers are tapered in a first direction to provide substantiallyconstant velocity air flow through the battery module.
 10. The batterymodule of claim 9, wherein the taper in the first direction of theexternal air chamber is opposite of the taper in the first direction ofthe central air chambers.
 11. The battery module of claim 1, wherein thebottom side of the lower tray further comprises multiple protrusionsextending from the bottom side of the lower tray through the chamber tothe bottom of the housing.
 12. The battery module of claim 1, furthercomprising an upper tray located inside the housing and adjacent a topof the housing and having a top side and a bottom side, the bottom sidehas a plurality of sockets configured to receive the plurality of cells.13. The battery module of claim 12, wherein the upper tray furthercomprises a plurality of openings to allow terminals of the cells topass through.
 14. The battery module of claim 13, wherein the top sideof the upper tray further comprises raised walls.
 15. The battery moduleof claim 14, wherein the raised walls include slots that allow sensorsto be connected to the plurality of cells.
 16. A battery modulecomprising: a plurality of cells; a housing configured to contain theplurality of cells; a lower tray located inside the housing adjacent abottom of the housing, the lower tray comprising a plurality of sockets,each socket configured to receive one of the plurality of cells; anupper tray located inside the housing adjacent a top of the housing; theupper tray comprising a plurality of sockets, each socket configured toreceive the corresponding cell from the lower tray; a common chamberdefined by a bottom of the lower tray and the bottom of the housing, thecommon chamber configured to receive gas expelled from the plurality ofcells; a seal located on an upper side of the lower tray and configuredto seal the connection between the plurality of cells and the lower trayto maintain the gas in the common chamber; and a clamping plate locatedabove the seal to clamp the seal between the lower tray and the clampingplate; wherein the housing includes an opening configured to fluidlyconnect the common chamber to atmosphere.
 17. The battery module ofclaim 16, wherein the plurality of cells are arranged into a first cellpack and a second cell pack, wherein a central air chamber is located inbetween the first cell pack and the second cell pack, a first externalair chamber is located between the first cell pack and a first side ofthe housing, and a second external air chamber is located between thesecond cell pack and a second side of the housing opposite the firstside of the housing.
 18. The battery module of claim 17, wherein thecentral air chamber is tapered in a first direction in order to providesubstantially constant velocity air flow through the battery module. 19.The battery module of claim 17, wherein the central air chamber istapered in a first direction and in a second direction in order toprovide substantially constant velocity air flow through the batterymodule.
 20. The battery module of claim 17, wherein the external airchambers are tapered in a first direction in order to providesubstantially constant velocity air flow through the battery module. 21.The battery module of claim 17, wherein the taper in the first directionof the external air chamber is opposite a taper of the first directionof the central air chambers.